Mark VIII Fan w/ DC Controller Not Working

[jknight16]

Hey guys, I'm nearing the end of my latest round of upgrades and have run into a snag with the Mark VIII fan and DC Controller.

I have checked the electrical connections and it appears everything is hooked up properly. With the key in accessory position, engine not running, I have a small signal voltage of .003 volts on the positive output side of the controller. 12.8 volts on the positive input side, and 12.3 volts on the yellow ignition wire. Grounds are good.

Should the fan run at all with the key in the accessory position, or should it run at all before the engine has gotten up to full temp?

Help!!

[BonzoHansen]

With a DCC the fan will not run until the sensor gets hot enough. But if you jump the blue wire it will run ~1/2 speed.

[FULMNTE]

I assume you bought a used fan?

First thing to do would have been to test it with a battery charger and see if it runs at all...

[jknight16]

well, i made up some wires to try to run the fan direct off the battery (Edit:) the fan did run, so it appears the fan is ok.

What kind of voltage are you supposed to see on the output side of the controller with the engine running and up to temp?

thanks guys.

[GetMore]

You will see battery voltage as the output from the controller. It doesn't matter what the temp, unless it's low enough that the controller is not driving the fan at all.
The control works by modulating pulse width, so it keep switching between full power and off, but really fast. The longer it is "on" versus "off" the faster the fan is driven.

Obviously the fan is your problem. You are correct that it really pulls when it's got power to it. Be careful, because it can have a little kick, and you don't want anything gettting caught in the blades.

There is a jumper for the control that makes it run at 10% minimum, if I remember correctly.
As the temperature increases the control is supposed to increase it's "on" time.

I'd make sure you have a good ground for the fan and try running it directly again, just to test it.
Then, when you are sure the fan is working and the wiring is correct, try hooking it up to the control again and seeing if that works.

[Jim Nilsen]

my mark viii fan would outdo my 110 volt 20" floor fan hooked up to my battery charger. I actually used it for a few nights instead of the floor fan to cool my garage. those fans really have a kick when started unbolted down so as was said be careful.

[jknight16]

I edited the post above because I tested the fan and it is working properly. It now appears the controller is my problem.

I'm only seeing .003 To .015 Volts on the positive output from the controller with the engine running and up to temp 180. It pulses up and down in that range, which seems appropriate, but the magnitude is obviously well below that of battery voltage.

I'm out of things to try myself. I'll email Brian and hope that I can get in contact with him. I wish this was the sort of thing where you could just order another one and have it overnighted, I need to have it running by Friday.

[jknight16]

I emailed Brian and he responded to my email inquiry in less than an hour. I thought this spoke very highly of his customer service and should be mentioned given that others have said he's difficult to get a hold of.

On his advice, I'm going to try adding the Underdrive Jumper on Pins 13/14 and/or see if hooking up the blue a/c wire to 12v (I don't have A/C, but will hook it up for testing purposes) has any impact on the fan operation.

[SamHatco]

You might want to read this thread...https://www.pro-touring.com/forum/showthread.php?t=53216. Kevin is pretty sharp when it comes to wiring the Mark VIII fan. He has helped me a lot. I'm working on a relay set up similar to his and should have it completed by the end of the week when I get all my parts in.

Sam

[jknight16]

Brian was of great help through email and I was able to get the controller and fan working. While it was spelled out clearly on the instructions, I glazed over the fact that you have to have the Underdrive pully jumper installed in order to get the 10% fan output with the key on. Installing that jumper allowed me to see that the fan and controller were in fact functioning together.

Now I just need to road test it to make sure the controller will ramp up appropriately, but I'm pretty confident it will.

[justanova]

Brian was of great help through email and I was able to get the controller and fan working. While it was spelled out clearly on the instructions, I glazed over the fact that you have to have the Underdrive pully jumper installed in order to get the 10% fan output with the key on. Installing that jumper allowed me to see that the fan and controller were in fact functioning together.

Now I just need to road test it to make sure the controller will ramp up appropriately, but I'm pretty confident it will.

thats good to hear, i think you will be happy with your choice